Optimization of packed bed solar air heaters—A thermo‐hydraulic approach

Abstract

AbstractThe present work deals with the thermo‐hydraulic optimization of solar heater with packed bed duct. Heat transfer and fluid flow characteristics of solar air heater have been analyzed to obtain optimal performance. The use of porous material in packed bed duct of solar air heater shows as an efficient method to enhance the thermal efficiency of solar air heaters. However, the use of packed bed results in higher friction factor requiring more pumping power, due to which, there is a need of optimization of the system to obtain maximum benefit from the packed bed. The present investigation has been emphasized on heat transfer and friction characteristics of solar air heater, provided with packed bed duct. Under thermo‐hydraulic consideration, relationship between system and operating parameters resulting in optimum performance has been developed, that can be utilized for the design of such thermo‐hydraulic optimized system. It is concluded that the enhancement factor slightly decreases with the increase in values of temperature rise parameter for every set of bed depth to packing element size ratios. For every set of bed depth to packing element size ratios, the maximum values of enhancement factors attains at (X1 = 0.009, X3 = 0.6), gives the optimal condition.